Optical block



FIG. 1 is a perspective view of the optical block showing our new design;

FIG. 2 is a side elevational view thereof, the opposite side being a mirror image thereof;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is an end elevational view.

The bottom view of the optical block illustrated in FIGS. 1-4 is hereby disclaimed and forms no part of the claimed design.

In the drawings, the broken line showing of the opposing end of the design as seen in FIG. 4 depicts environmental subject matter and forms no part of the claimed design. 

CLAIM The ornamental design for an optical block, as shown and described, except as disclaimed herein. 